The present invention relates generally to a splitter, also called riving knife system, used on table saw with quick release device for change over of splitter and/or riving knife.
Woodworking machines such as table saws typically have a splitter behind the saw blade, to hold cut work pieces from closing and to prevent the accidental “kickback” of work pieces that are thrown back to the operators, which often times result in injury to the operators.
Traditionally, most of the splitters are mounted on the work table of the table saw; consequently, there are two main disadvantages: one, the splitter does not maintain a constant distance to the saw blade as the blade is being adjusted for different heights; two, if different splitter is needed (for example, to correspond to different arc radius or thickness of different saw blade), the task for the changeover, removal and/or putting in new splitter is difficult and time-consuming.
In a non-through cutting scenario (groove cutting), this type of surface-mounted splitter has to be removed, for the intended groove to be cut. In this case, only a riving knife that is “mounted” to the housing for the saw blade can fit the purpose of the cut. However, the current splitter system on the market requires about 20 minutes or longer to make the change over from splitter to riving knife, and it normally requires proper tools to make the change. Operators, in their attempt to save time, sometimes would forego the installation of riving knife and simply start working on work pieces after splitter is removed, greatly enhancing possibility for the injuries that can be brought about by the “kickback” of work pieces.
Also the current riving knife system on the market does not maintain a constant height difference between the saw blade and the riving knife which is very important for effective prevention of kickbacks. Whenever the saw blade is set to different height (to cut different groove, for example), a separate effort to adjust the position of the riving knife is required, after the effort of adjusting the saw blade is done. This time-consuming work also very likely prevent operator from using riving knife for non-through cutting.
To reach a better safety standard, the trend in the woodworking industry is to have properly shaped and designed splitter and/or riving knife that move with the blade in a synchronized manner, so that at any adjusted blade position, the splitter/riving knife will stay in certain linear distance relative to the blade (range from 3-8 mm, with 5 mm being the norm) resulting in a constant and safe working condition for the operators. Also, it would be a desirable feature to shorten the time spent on the changeover from splitter to riving knife, and vice versa. Preferably, the market would appreciate a changeover time of less than 30 seconds. The short changeover time will be of greater value, when no tools is needed, as disclosed and taught in present invention.
To respond to this market trend and preference, present invention deals with the problems of current splitter/riving knife system on the market, by using a unique multi-gear system to keep the splitter/riving knife at a constant linear difference to the saw blade, and a spring pressure plate mechanism for easy changeover and installation of splitter and riving knife without tools.
For the need to put in new splitter or riving knife, or have a changeover from a splitter to a riving knife, present invention disclosed a system of quick release and installation by way of a spring pressure plate with lug nuts securing the riving knife quickly to a pre-determined position.
The riving knife will have a guide slot that slides into the middle lug nut, while having two lug nuts adjacent to the outside edge, making the task of alignment for the newly inserted riving knife very simple and intuitive, thus promoting the proper use of the riving knife and greatly enhancing the safety for the operator of such wood working machines. All these operations will require no tools and will usually take less than 10 seconds.